You "complete the square" to get rid of a term of the form "ax", that is x to the 1 power, in a quadratic. In your example, , there is no "x" term- " " is already a perfect square. The minimum value occurs when x= 0 and is -25. Since the graph of is a parabola with vertex at (0, -25), vertical axis, opening upward, and with x-intercepts at (5/2, 0) and (-5/2, 0).